/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.runtime.partitioner;

import org.apache.flink.runtime.plugable.SerializationDelegate;
import org.apache.flink.streaming.runtime.partitioner.StreamPartitioner;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
import org.apache.flink.table.dataformat.BaseRow;
import org.apache.flink.table.dataformat.BinaryRow;
import org.apache.flink.table.runtime.generated.GeneratedHashFunction;
import org.apache.flink.table.runtime.generated.HashFunction;
import org.apache.flink.util.MathUtils;

import java.util.Arrays;

/**
 * Hash partitioner for {@link BinaryRow}.
 */
public class BinaryHashPartitioner extends StreamPartitioner<BaseRow> {

	private GeneratedHashFunction genHashFunc;

	private transient HashFunction hashFunc;
	private String[] hashFieldNames;

	public BinaryHashPartitioner(GeneratedHashFunction genHashFunc, String[] hashFieldNames) {
		this.genHashFunc = genHashFunc;
		this.hashFieldNames = hashFieldNames;
	}

	@Override
	public StreamPartitioner<BaseRow> copy() {
		return this;
	}

	@Override
	public int selectChannel(SerializationDelegate<StreamRecord<BaseRow>> record) {
		return MathUtils.murmurHash(
				getHashFunc().hashCode(record.getInstance().getValue())) % numberOfChannels;
	}

	private HashFunction getHashFunc() {
		if (hashFunc == null) {
			try {
				hashFunc = genHashFunc.newInstance(Thread.currentThread().getContextClassLoader());
				genHashFunc = null;
			} catch (Exception e) {
				throw new RuntimeException(e);
			}
		}
		return hashFunc;
	}

	@Override
	public String toString() {
		return "HASH" + Arrays.toString(hashFieldNames);
	}
}
